In an environment for producing an electronic board, such as a semiconductor wafer, liquid crystal board, magnetic disc and the like (hereinafter, referred to as board), contaminants, such as an acidic substance, basic substance and the like in its production space are adsorbed on a board to cause lowering of the yield of a product and reduction in its quality, thus, a step of producing such a board is carried out in a clean room. It is necessary to evaluate the contaminated condition by the above-described acidic substance, basic substance and the like in the clean room in each production process, and examples of the evaluation means include a method in which air in a clean room sucked by a suction pump is passed through an absorption solution at a constant flow rate to allow contaminants in the air to be absorbed, and the absorbed contaminants are analyzed, a method in which air in a clean room sucked by a suction pump is passed through a filter at a constant flow rate to allow contaminants in the air to be adsorbed, the contaminants are removed from the filter with a solvent, and the removed contaminants are analyzed, and the like (see, e.g., non-patent documents 1 and 2, patent document 1).
Recently, a clean room is required to ensure a more highly cleaned space, together with a need for a method of evaluating the contaminated condition by an acid or base with high sensitivity.    [Non-patent document 1] “Appendix 1: method of measuring acidic substance in clean room and associated controlled environment air”, JACA No. 35A-2003: guideline of notation method and measurement method of air cleanliness relating to molecular contaminants in clean rooms and associated controlled environments, Japan Air Cleaning Association, 2003, March 1, p. 5-6    [Non-patent document 2] “Appendix 2: method of measuring basic substance in clean room and associated controlled environment air”, JACA No. 35A-2003: guideline of notation method and measurement method of air cleanliness relating to molecular contaminants in clean rooms and associated controlled environments, Japan Air Cleaning Association, 2003, March 1, p. 7-9    [Patent document 1] JP-A No. 2003-222577